In a newly proposed LTE-Hi (Long Term Evolution-Hi, Long Term Evolution-Hi) architecture, a user equipment (User Equipment, UE) may access a core network via an evolved NodeB (evolved NodeB, eNB), or may connect to the eNB via an LTE-Hi access point (LTE-Hi Access Point, LTE-Hi AP) and then access the core network via the eNB. The UE may also directly connect to a gateway device on another network via the LTE-Hi AP. In the LTE-Hi architecture, the UE has two radio air interfaces, that is, a Uu air interface between the UE and the eNB and a Uu′ air interface between the UE and the LTE-Hi AP.
The LTE-Hi architecture not only can support the scenario in which the UE performs access initially from the LTE-Hi AP and then some services are transferred to the eNB, but also can support the scenario in which the UE performs access initially from the eNB and then some services are transferred to the LTE-Hi AP. Therefore, an air interface security mechanism for the Uu′ air interface needs to be compatible with the foregoing two scenarios. The UE may receive data through two links corresponding to the Uu′ air interface and the Uu air interface at the same time to communicate with the LTE-Hi AP and the eNB at the same time. In such a scenario, two branches have their own air interfaces. Generation, maintenance, modification and deletion of an access stratum (Access Stratum, AS) security context on the two air interfaces need to be considered to ensure security of data transmitted over each air interface.
However, in the prior art, only a manner of generating an AS key on the Uu air interface is provided, while how to generate the AS key on the Uu′ air interface is not involved. As a result, security of data transmission over the Uu′ air interface cannot be ensured.